U.S. patent number 5,310,731 [Application Number 06/742,565] was granted by the patent office on 1994-05-10 for n-6 substituted-5'-(n-substitutedcarboxamido)adenosines as cardiac vasodilators and antihypertensive agents.
This patent grant is currently assigned to Whitby Research, Inc.. Invention is credited to Ray A. Olsson, Robert D. Thompson.
United States Patent |
5,310,731 |
Olsson , et al. |
May 10, 1994 |
N-6 substituted-5'-(N-substitutedcarboxamido)adenosines as cardiac
vasodilators and antihypertensive agents
Abstract
Compounds of the formula ##STR1## are disclosed, wherein
R.sub.1, represents secondary alkyl; aralkyl; cycloalkyl;
heteroaryl substituted alkyl; norbornyl; and substituted secondary
alkyl, aralkyl, cycloalkyl, heteroaryl substituted alkyl,
norbornyl; and para-substituted phenyl groups; and R.sub.2 and
R.sub.3 are hydrogen or pharmacologically acceptable acyl groups.
The compounds of the invention are useful as cardiovascular
vasodilator or anti-hypertensive agents. The therapeutically useful
compounds of the invention as well as similar 5'-N and N-6
substituted adenosine 5'-uronamides are prepared, in accordance
with a novel process, from isopropylidene (or otherwise suitably
blocked) inosine-5' -uronic acid. Isopropylideneinosine-5' -uronic
acid is reacted with a suitable inorganic acid halide, such as
thionyl chloride, to yield 6-halogeno-9-[ 2',3'
-O-isopropylidene-.beta.-D-ribofuranosyl-5-uronic acid halide]
-9H-purine. This intermediate is reacted with an amine of the
general formula R.sub.4,R.sub.5 NH to give a 6-halogeno
substituted, substituted uronic acid amide of the formula ##STR2##
wherein X is halogen. Reaction of the latter intermediate with an
amine of the formula R.sub.1 --NH.sub.2, and removal of the
isopropylidene (or other) blocking groups yields the compounds of
the invention.
Inventors: |
Olsson; Ray A. (Odessa, FL),
Thompson; Robert D. (Irvine, CA) |
Assignee: |
Whitby Research, Inc.
(Richmond, VA)
|
Family
ID: |
27089928 |
Appl.
No.: |
06/742,565 |
Filed: |
June 12, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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625450 |
Jun 28, 1984 |
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Current U.S.
Class: |
514/46; 514/45;
536/27.22 |
Current CPC
Class: |
C07H
19/16 (20130101) |
Current International
Class: |
C07H
19/16 (20060101); C07H 19/00 (20060101); A61K
031/70 (); C07H 019/167 () |
Field of
Search: |
;514/46 ;536/26,27 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2007273 |
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Aug 1971 |
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DE |
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0677630 |
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Apr 1968 |
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ZA |
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Other References
Goodman, "Chemical Syntheses and Transformations of Nucleosides" in
Basic Principles in Nucleic Acid Chemistry, P. O. P. Ts'O ed.,
Academic Press, New York, 1974, see pp. 150-151. .
Schmidt and Fritz, Chem Ber 103, 1867-1871 (1970). .
Fox and Kurpis, The Journal of Biological Chemistry, vol. 258, No.
11, Issue of Jun. 10, pp. 6952-6955 (1983). .
Schuske, U., In Berne et al, Ch 6 of "Regulatory Function of
Adenosine" (London) (Pub) pp. 77-96, 1983, Martinus Nishoff. .
Stein et al, N.Y. Acad. Sci, 255, 380-389, 1975. .
Daly, J. Med. Chem., 25(3), pp. 197-207, 1982. .
Stein, J. Med. Chem., 16(11), pp. 1306-1309, 1973. .
J. W. Daly, et al., "Structure-Activity Relationships for N.sup.6
-Substituted Adenosine at a Brain A.sub.1 -Adenosine Receptor with
a Comparison to an A.sub.2 -Adenosine Receptor Regulating Coronary
Blood Flow," Biochemical Pharmacology, vol. 35, No. 15, pp.
2467-2481, 1986. .
Chemical Abstract 72:3706. .
R. A. Olsson, et al., "Use of Structure-Activity Relationship in
the Study of Adenosine Receptors," Methods of Pharm. vol. 6,
1985..
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Primary Examiner: Brown; Johnnie R.
Assistant Examiner: Crane; L. Eric
Attorney, Agent or Firm: Baran; Robert J. Hackler; Walter
A.
Parent Case Text
BACKGROUND OF THE INVENTION
1. Cross-reference to Related Application
The present application is a continuation-in-part of application
Ser. No. 625,450 filed on Jun. 28, 1984, now abandoned by the same
inventors, and assigned to the same assignee as the present
application.
Claims
What is claimed is:
1. Compounds of the formula: ##STR9## wherein: R.sub.1 represents
secondary alkyl having from 3 to 10 carbons, phenylalkyl, having
from 1 to 7 carbons in the alkyl chain; mono- to penta-alkoxy
phenylalkyl wherein said alkoxy contains from 1 to 3 carbons and
said alkyl contains from 1 to 7 carbons; monohalophenylalkyl
wherein said alkyl contains from 1 to 4 carbons; cycloalkyl wherein
the ring contains from 3 to 8 carbons; bicycloalkyl wherein the
rings together contain from 7 to 10 carbons; thienylalkyl wherein
said alkyl contains from one to four carbons; pyridylalkyl wherein
said alkyl contains from one to four carbons;
R.sub.2 and R.sub.3 are hydrogen;
R.sub.4 is alkyl having 1 to 7 carbon atoms; or hydroxyalkyl which
contains from 1 to 4 carbons; or secondary alkyl which contains
from 3-8 carbons; or allylic alkenyl which contains from 3 to 7
carbons; or cycloalkyl wherein the ring contains from 3 to 7
carbons; or phenylalkyl wherein said alkyl contains from 1 to 4
carbons; or monoalkoxy phenylalkyl wherein said alkoxy and said
alkyl each contain from 1 to 4 carbons; or thienylalkyl wherein
said alkyl contains from 1 to 4 carbons; and R.sub.5 is hydrogen,
or straight chain lower alkyl having 1 to 4 carbons.
2. Compounds of claim 1 wherein R.sub.4 is methyl or ethyl.
3. Compounds of claim 1 wherein R.sub.1 is endo-2-norbornyl,
R.sub.4 is 2-hydroxyethyl and R.sub.5 is hydrogen.
4. Compounds of claim 1 wherein R.sub.4 is ethyl and R.sub.5 is
hydrogen.
5. Compounds of claim 4 wherein R.sub.1 is cyclohexyl.
6. Compounds of claim 4 wherein R.sub.1 is
(S)-1-phenyl-2-butyl.
7. Compounds of claim 4 wherein R.sub.1 is 4-methoxyphenyl.
8. Compounds of claim 4 wherein R.sub.1 is
2-(3,4,5-trimethoxyphenyl)-ethyl.
9. Compounds of claim 4 wherein R.sub.1 is 3-phenylpropyl.
10. Compounds of claim 4 wherein R.sub.1 is (R)-1-phenyl-ethyl.
11. Compounds of claim 4 wherein R.sub.1 is 2-(2-pyridyl)ethyl.
12. Compounds of claim 4 wherein R.sub.1 is
(2-chloro-phenyl)-methyl.
13. Compounds of claim 4 wherein R.sub.1 is (2-thienyl)methyl.
14. Compounds of claim 4 wherein R.sub.1 is
(R)-1-phenyl-2-propyl.
15. The compounds of claim 1 wherein R.sub.4 is
Z--Q--(CH.sub.2).sub.n wherein n is an integer having the values of
1 to 4; Q is selected from the group consisting of phenyl, thienyl,
or pyridyl, and Z is one or more H, hydroxy, halogen, alkoxy having
from 1 to 4 carbon atoms, or alkyl having from 1 to 7 carbon
atoms.
16. Compounds of claim 1 wherein R.sub.1 is ##STR10##
17. Compounds of claim 16 wherein R.sub.4 is ethyl, R.sub.5 is
H.
18. Compounds of claim 16 wherein R.sub.4 is methyl, R.sub.5 is
H.
19. Compounds of claim 16 wherein R.sub.4 is isopropyl, R.sub.5 is
H.
20. Compounds of claim 16 wherein R.sub.4 is 3-pentyl, R.sub.5 is
H.
21. Compounds of claim 16 wherein R.sub.4 is allyl, R.sub.5 is
H.
22. Compounds of claim 16 wherein R.sub.4 is (2-methyl) propyl,
R.sub.5 is H.
23. Compounds of claim 16 wherein R.sub.4 is cyclopropyl, R.sub.5
is H.
24. Compounds of claim 16 wherein R.sub.4 is phenylmethyl, R.sub.5
is H.
25. Compounds of claim 16 wherein R.sub.4 is 2-methoxyphenylmethyl,
R.sub.5 is H.
26. Compounds of claim 16 wherein R.sub.4 is 2-thienylmethyl,
R.sub.5 is H.
27. Compounds of claim 16 wherein R.sub.4 is 2-phenylmethyl,
R.sub.5 is H.
28. Compounds of claim 16 wherein R.sub.4 is methyl, R.sub.5 is
methyl.
29. Compounds of claim 16 wherein R.sub.4 is n-butyl, R.sub.5 is
methyl.
30. Compounds of claim 16 wherein R.sub.4 is ethyl, R.sub.5 is
ethyl.
31. Compounds of claim 1 wherein R.sub.1 is ##STR11## and R.sub.4
and R.sub.5 are methyl.
32. A pharmaceutical composition comprising a compound of claim 1
in admixture with one or more pharmaceutically acceptable
carriers.
33. A method of administering to humans or animals of the mammalian
species a vasodilator or anti-hypertensive compound in a
therapeutically effective does to achieve a vasodilatory or
anti-hypertensive effect, the compound having the formula ##STR12##
wherein: R.sub.1 represents secondary alkyl having from 3 to 10
carbons; phenylalkyl, having from one to seven carbon atoms in the
alkyl chain; mono- to penta-alkoxy phenylalkyl wherein said alkoxy
contains from 1 to 3 carbons and said alkyl contains from 1 to 7
carbons; monohalophenylalkyl wherein said alkyl contains from 1 to
4 carbons; cycloalkyl wherein the ring contains from 3 to 8
carbons; bicycloalkyl wherein the rings together contain from 7 to
10 carbons; thienylalkyl wherein said alkyl contains from one to
four carbons; pyridylalkyl wherein said alkyl contains from one to
four carbons;
R.sub.2 and R.sub.3 are hydrogen;
R.sub.4 is alkyl having 1 to 7 carbon atoms; or hydroxyalkyl which
contains from 1 to 4 carbons; or secondary alkyl which contains
from 3-8 carbons; or allylic alkenyl which contains from 3 to 7
carbons; or cycloalkyl wherein the ring contains from 3 to 7
carbons; or phenylalkyl wherein said alkyl contains from 1 to 4
carbons; or monoalkoxy phenylalkyl wherein said alkoxy and said
alkyl each contain from 1 to 4 carbons; or thienylalkyl wherein
said alkyl contains from 1 to 4 carbons; and
R.sub.5 is hydrogen, or straight chain lower alkyl having 1 to 4
carbons.
34. The method of claim 33 wherein in the formula of the
administered compound R.sub.4 is ethyl and R.sub.5 is hydrogen.
35. The method of claim 33 wherein in the formula of the
administered compound R.sub.1 is 3-pentyl.
Description
2. Field of the Invention
The present invention is directed to certain N-6 and 5'-N
substituted carboxamidoadenosine derivatives which have beneficial
cardiovascular and antihypertensive activity in mammals, including
humans and domestic animals. The present invention is also directed
to a process for making said compounds.
3. Brief Description of the Prior Art
Adenosine has been known for a long time to possess certain
cardiovascular activity and particularly coronary dilatory
activity. In an effort to obtain adenosine analogs of greater
potency, or longer duration of activity, or both, many analogs of
this naturally occurring nucleoside have been synthesized and
tested.
Moreover, numerous studies have been conducted in order to
elucidate the biochemical mechanism of action of adenosine and its
analogs, and several theories and hypotheses have been proposed
regarding biochemical pathways and receptor sites.
For discussion of current theories regarding the foregoing,
reference is made to the following articles and publications:
Adenosine Receptors: Targets for Future Drugs, by John W. Daly,
Journal of Medicinal Chemistry, 25, 197 (1982); Cardiovascular
Effects of Nucleoside Analogs, by Herman H. Stein and Pitambar
Somani, Annals New York Academy of Sciences, 255, 380 (1979);
Coronary Dilatory Action of Adenosine Analogs: a Comparative Study,
by G. Reberger, W. Schutz and O. Kraupp, Archives internationales
de Pharmacodynamie et de Therapie 230, 140-149 (1977); Chapter 6 of
the book titled: Regulatory Function of Adenosine, (pages 77-96),
R. M. Berne, T. W. Rall and R. Rubio editors, Martinus Nijhoff
publishers, The Hague/Boston/London; Ethyl
Adenosine-5'-carboxylate: A Potent Vasoactive Agent in the Dog, by
Herman H. Stein, Journal of Medicinal Chemistry, 16, 1306 (1973);
Modification of the 5' Position of Purine Nucleosides: 2. Synthesis
and Some Cardiovascular Properties of
Adenosine-5'-(N-substituted)carboxamides, by Raj N. Prasad et al.,
Journal of Medicinal Chemistry, 23, 313 (1980); and Modification of
the 5' Position of Purine Nucleosides: 1. Synthesis and Biological
Properties of Alkyl Adenosine-5'-carboxylates by Raj N. Prasad et
al., Journal of Medicinal Chemistry, 19, 1180 (1976).
In addition to the foregoing publications, German
Offenlegungschrift Nos. 2133273, 2426682, 1795761, 1913818,
2007273, 2238923, 2060189, 2244328, 1814711, 2136624, South African
Patent Application No. 677630 (filed on Dec. 20, 1967) and British
Patent Specification No. 1,123,245 describe adenosine derivatives
which have cardiovascular, coronary dilator or antilipolytic
activities. Still more adenosine derivatives having beneficial
cardiovascular activity are described in another application for
U.S. Letters Patent of the present inventors, Ser. No. 601,435,
filed on Apr. 18, 1984.
Still further, Published Japanese Patent Application Nos. 58-167599
and 58-167600 disclose adenosine 5'-carboxamide derivatives which
have fibrinolysis accelerating activity. U.S. Pat. No. 4,029,334
discloses anti-hypertensive and anti-anginal adenosine
5'-carboxamide derivatives where the N.sup.6 amino group is
unsubstituted. U.S. Pat. No. 4,167,565 discloses adenosine
5'-carboxamide derivatives which have substituents both in the
N.sup.6 and 5'-carboxamido position, and which are useful as
poisons for certain noxious animals, such as rodents and
coyotes.
In the cardiovascular and anti-hypertensive field, however, the
therapeutic utility of the natural nucleoside adenosine and many of
its analogs is limited because the desired beneficial effect is
often of relatively short duration.
More particularly, the short duration of the beneficial
cardiovascular effects of adenosine and those of its analogs which
have an unsubstituted hydroxyl group at C-5 of the ribofuranose
moiety is usually attributed to rapid penetration into cells
followed by enzymatic conversion into less active or impermeant
metabolites. For example, adenosine deaminase converts adenosine
into inosine, which is a weak cardiovascular agonist.
Alternatively, phosphorylation, catalyzed by adenosine kinase,
forms adenylic acid (5'-AMP). Ionization of the phosphate group
under physiological conditions prevents the escape of 5'-AMP from
the cells in which it is formed. Thus trapped, 5'-AMP cannot exert
its cardiovascular actions, which are mediated by cell surface
receptors, as is discussed below.
Some known adenosine analogs, however, cannot be phosphorylated in
the 5' position because the 5' position is effectively blocked.
5'-N-Ethylcarboxamidoadenosine [NECA] (Compound 1 in General
Formula 1) is an example of such an adenosine analog incapable of
phosphorylation by adenosine kinase. Nevertheless, this compound
binds potently to certain adenosine receptor sites and exhibits
substantial cardiovascular activity. Other examples of known
derivatives of adenosine-5'-carboxamide, (Compound 2) and of
adenosine-5'-carboxylic acid (Compound 9) are shown below in
General Formulae 1 and 2. Generally speaking, in these compounds,
the 5'-carboxylate or 5'-carboxamide group of the uronic acid
moiety is substituted with lower alkyl or lower acyl groups. Some
of the adenosine-5'-carboxamide derivatives shown in General
Formula 1 are disclosed in Chemical Abstracts Volume 100, 68652c
and 68653d (1984) and in the corresponding Published Japanese
Patent Application Nos. 58-167599 and 58-167600.
The biological activity of adenosine-5'-carboxamide derivatives,
such as NECA, is thought to be due to the activation of adenylate
cyclase through cell surface "R.sub.a " or "A.sub.2 " receptors.
Structure-activity studies show that the R.sub.a receptor
recognizes the alkyl uronamide moiety of NECA and its congeners. A
second type of cell surface adenosine receptor designated "R.sub.i
" or "A.sub.1 " inhibits the catalytic activity of adenylate
cyclase. Adenosine analogs possessing certain N-6 alkyl or aralkyl
substituents such as cyclohexyl or R-1-phenyl-2-propyl are
selective agonists at R.sub.i receptors. Many mammalian and human
cells contain both R.sub.a and R.sub.i receptors; examples of
exceptions are fat cells which contain R.sub.i receptors only, and
blood platelets and human placenta, in which R.sub.a receptors
predominate.
Currently available agonists are only selective, not absolutely
specific, for R.sub.a and R.sub.i receptors. Because the two types
of receptors coexist in many organs, including brain and heart,
even a selective agonist will activate both to a certain degree. A
goal of pharmaceutical chemistry is the development of agonists
which are as nearly specific as possible because unselectivity can
be a source of side effects.
The prior art makes no prediction about receptor selectivity of
adenosine analogs which contain, in the same molecule, the
recognition groups which confer specificity for R.sub.a and R.sub.i
receptors. ##STR3##
Many of the known adenosine derivatives, including the above-noted
N-6 substituted and the 5'-carboxamide derivatives are less than
satisfactory as cardiovascular or antihypertensive drugs for animal
and human use. This is either because of low activity, short
duration of the desired activity, undue toxicity or undesirable
side effects. Undesirable side effects of cardiovascularly active
adenosine analogs often include cardiac depression.
In light of the foregoing, the pharmaceutical industry is still
striving to obtain adenosine analogs having high cardiovascular and
hypotensive potency coupled with other optimal physiological
characteristics, such as relatively long duration of the desired
activity, low toxicity and minimal side effects. The compounds of
the present invention constitute a step in this direction.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide adenosine
analogs which have potent and prolonged cardiovascular activity in
mammals and humans, coupled with relatively low toxicity and
minimal side effects.
It is another object of the present invention to provide adenosine
analogs which have potent or prolonged anti-hypertensive activity
in mammals and humans, coupled with relatively low toxicity and
minimal side effects.
It is still another object of the present invention to provide a
relatively efficient synthetic process for the preparation of the
adenosine derivatives which meet the above-noted objectives.
The foregoing and other objects and advantages are attained by
compounds of the General Formula 3, wherein R.sub.1 represents
secondary alkyl; hydroxy, lower alkoxy or halogen substituted
secondary alkyl; aralkyl; aralkyl substituted in the aromatic
nucleus with hydroxy, halogen, lower alkoxy or lower alkyl groups;
cycloalkyl; hydroxy, lower alkoxy, lower alkyl or halogen
substituted cycloalkyl; para-substituted phenyl; heteroaryl
substituted alkyl; heteroaryl substituted alkyl substituted in the
heteroaryl nucleus with hydroxy, halogen, lower alkoxy or lower
alkyl groups; norbornyl, and hydroxy, alkyl or halogen substituted
norbornyl groups.
The substituent R.sub.2 and R.sub.3 groups in the compounds of the
present invention, as shown in General Formula 3, are hydrogen, or
pharmacologically acceptable organic acyl groups, or inorganic acid
radicals, such as NO.sub.2 groups, which esterify the hydroxyl
groups of the ribofuranose moiety. The R.sub.2 and R.sub.3 groups
are preferably of the type which are relatively readily hydrolyzed
under physiological conditions. The R.sub.2 and R.sub.3
substituents need not be identical with one another.
Still further, in the compounds of General Formula 3, the
substituent R.sub.4 is straight chain lower alkyl having 1-4 carbon
atoms; hydroxy, lower alkoxy or halogen substituted straight chain
lower alkyl having 1-4 carbon atoms; cyclopropyl; secondary alkyl
having 3-6 carbon atoms; hydroxy, lower alkoxy or halogen
substituted secondary alkyl having 3-6 carbon atoms; alkenyl having
3 to 6 carbon atoms; aralkyl having 1 to 4 carbons in the alkyl
chain; aralkyl having 1 to 4 carbons in the alkyl chain and
substituted in the aryl nucleus with hydroxy, halogen, lower alkoxy
or lower alkyl groups; heteroarylalkyl having 1 to 4 carbons in the
alkyl chain; and heteroarylalkyl having 1 to 4 carbons in the alkyl
chain and substituted in the heteroaryl nucleus with hydroxy,
halogen, lower alkoxy or lower alkyl groups. R.sub.5 is hydrogen,
or straight chain lower alkyl having 1 to 4 carbons. ##STR4##
The compounds of the present invention are resistant to enzymatic
phosphorylation and to deamination by adenosine deaminase. The
compounds exhibit significant cardiovascular activity.
In accordance with a novel process of the invention, the compounds
of General Formula 3 are obtained from
2',3'-O-isopropylideneinosine-5'-uronic acid by treatment with a
suitable inorganic acid halide, such as thionyl chloride, to yield
the intermediate,
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl-5-ur onic
acid chloride]-9H-purine. The intermediate,
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl-5-uronic
acid chloride]-9H-purine, (or the corresponding bromide, if, for
example thionyl bromide is used instead of thionyl chloride) is
usually not isolated in a pure state.
The acid chloride moiety of
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl-5-uronic
acid chloride]-9H-purine (or the acid bromide of the corresponding
bromo- analog) is significantly more readily displaced by
nucleophilic reagents than the halide group in the 6 position of
the purine moiety. Therefore, in accordance with the process of the
present invention,
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl-5-uronic
acid chloride]-9H purine is reacted with a first nucleophilic
reagent having the formula R.sub.4,R.sub.5 -NH (General Formula 4)
to yield an intermediate substituted carboxamide shown in General
Formula 5, wherein the halide is retained in the 6position of the
purine moiety.
The intermediate of General Formula 5 is subsequently reacted with
a nucleophile having the formula R.sub.1 - NH.sub.2 (General
Formula 6) and the isopropylidene blocking group is removed with
acid to yield the compounds of the invention (General Formula 3),
having free hydroxyl groups in the 2' and 3' positions of the
ribofuranose moiety. Instead of the isopropylidene blocking group,
other acid stable blocking groups can also be used to protect the
2'--OH and 3'--OH groups of the ribofuranose moiety during the step
of treatment with the inorganic acid halide.
The groups R.sub.1, R.sub.4 and R.sub.5 in General Formulae 4-6 are
defined the same as in General Formula 3. ##STR5##
DETAILED DESCRIPTION OF THE INVENTION
Certain derivatives of 5'-carboxamidoadenosine wherein both the
amino nitrogen (N-6) of the purine moiety and the amino nitrogen of
the 5'-carboxamido moiety are substituted, have been found, in
accordance with the present invention, to possess significant
cardiovascular and/or anti-hypertensive activity. The compounds of
the invention have the composition characterized by General Formula
3. The substituent R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5
groups are defined above in the summary description of the present
invention.
A preferred subclass of the compounds of the present invention
consists of N-6 substituted derivatives of
5'-N-ethylcarboxamidoadenosine shown in General Formula 7, wherein
the R.sub.1 substituents of the N-6 amino nitrogen comprise:
secondary alkyl; hydroxy, lower alkoxy or halogen substituted
secondary alkyl; aralkyl; aralkyl substituted in the aromatic
nucleus with hydroxy, halogen, lower alkoxy or lower alkyl groups;
cycloalkyl; hydroxy, lower alkoxy, lower alkyl or halogen
substituted cycloalkyl; para-substituted phenyl; heteroaryl
substituted alkyl; heteroaryl substituted alkyl substituted in the
heteroaryl nucleus with hydroxy, halogen, lower alkoxy or lower
alkyl groups.
The R.sub.2 and R.sub.3 substituent groups on the 2' and 3'
positions of the ribofuranose moiety are hydrogen, or
pharmaceutically acceptable acyl groups, such as acetyl, propionyl,
butyryl and benzoyl groups. Especially preferred in this regard,
are those acyl groups which are relatively readily split off the
ribofuranose moiety under physiological conditions. The R.sub.2 and
R.sub.3 substituent groups can also represent inorganic acid
radicals, such as NO.sub.2 groups, which esterify the hydroxyl
groups of the ribofuranose moiety.
The R.sub.4 substituent in the foregoing subclass of compounds
shown in General Formula 7, is hydrogen, methyl or ethyl.
Another preferred subclass of the compounds of the present
invention consists of derivatives of 5'-carboxamidoadenosine,
compounds of General Formula 8, wherein both the N-6 and
5'-carboxamido nitrogens are monosubstituted with the substituents
R.sub.1 and R.sub.4 respectively, and where the R.sub.2 and R.sub.3
substituents are defined the same as for the compounds of General
Formula 7.
In this preferred subclass of compounds, shown in General Formula
8, the R.sub.1 substituents are: secondary alkyl; hydroxy, lower
alkoxy or halogen substituted secondary alkyl; aralkyl; aralkyl
substituted in the aromatic nucleus with hydroxy, halogen, lower
alkoxy or lower alkyl groups; cycloalkyl; hydroxy, lower alkoxy,
lower alkyl or halogen substituted cycloalkyl; para-substituted
phenyl; heteroaryl substituted alkyl; heteroaryl substituted alkyl
substituted in the heteroaryl nucleus with hydroxy, halogen, lower
alkoxy or lower alkyl groups.
The substituents R.sub.4 of the preferred subclass shown in General
Formula 8 are: straight chain lower alkyl having 1-4 carbon atoms;
hydroxy, lower alkoxy or halogen substituted straight chain lower
alkyl having 1-4 carbon atoms; cyclopropyl; secondary alkyl having
3-6 carbon atoms; hydroxy, lower alkoxy or halogen substituted
secondary alkyl having 3-6 carbon atoms; alkenyl having 3 to 6
carbon atoms.
Specific examples of preferred compounds of this subclass (General
Formula 8) are those where the R.sub.1 (N-6) and R.sub.4
(5'-carboxamido) substituents are as follows, with R.sub.2 and
R.sub.3 being hydrogen:
Compound 17: R.sub.1 is 3-pentyl, R.sub.4 is ethyl;
Compound 18: R.sub.1 is cyclohexyl, R.sub.4 is ethyl;
Compound 19: R.sub.1 is (S)-1-phenyl-2-butyl, R.sub.4 is ethyl;
Compound 20: R.sub.1 is 4-methoxy-phenyl, R.sub.4 is ethyl;
Compound 21: R.sub.1 is 2-(3,4,5-trimethoxyphenyl)ethyl, R.sub.4 is
ethyl;
Compound 22: R.sub.1 is 3-phenyl-propyl, R.sub.4 is ethyl;
Compound 23: R.sub.1 is (R)-1-phenylethyl, R.sub.4 is ethyl;
Compound 24: R.sub.1 is 2-(2-pyridyl)ethyl, R.sub.4 is ethyl;
Compound 25: R.sub.1 is (2-chlorophenyl)methyl, R.sub.4 is
ethyl;
Compound 26: R.sub.1 is (2-thienyl)methyl, R.sub.4 is ethyl;
Compound 27: R.sub.1 is endo-2-norbornyl, R.sub.4 is
2-hydroxyethyl;
Compound 28: R.sub.1 is 3-pentyl, R.sub.4 is methyl;
Compound 29: R.sub.1 is 3-pentyl, R.sub.4 is isopropyl;
Compound 30: R.sub.1 is 3-pentyl, R.sub.4 is 3-pentyl;
Compound 31: R.sub.1 is 3-pentyl, R.sub.4 is allyl;
Compound 32: R.sub.1 is 3-pentyl, R.sub.4 is (2-methyl)propyl;
Compound 33: R.sub.1 is 3-pentyl, R.sub.4 is cyclopropyl;
Compound 34: R.sub.1 is (R)-1-phenyl-2-propyl, R.sub.4 is
ethyl;
A preferred subgroup within the subclass shown by General Formula 8
comprise compounds in which the 5'-carboxamido group is ethyl
substituted. With reference to General Formula 8, specific examples
of compounds of this subgroup are:
Compound 17: R.sub.1 is 3-pentyl, R.sub.4 is ethyl;
Compound 18: R.sub.1 is cyclohexyl, R.sub.4 is ethyl;
Compound 19: R.sub.1 is (S)-1-phenyl-2-butyl, R.sub.4 is ethyl;
Compound 20: R.sub.1 is 4-methoxy-phenyl, R.sub.4 is ethyl;
Compound 21: R.sub.1 is 2-(3,4,5-trimethoxyphenyl)ethyl, R.sub.4 is
ethyl;
Compound 22: R.sub.1 is 3-phenylpropyl, R.sub.4 is ethyl;
Compound 23: R.sub.1 is (R)-1-phenylethyl, R.sub.4 is ethyl;
Compound 24: R.sub.1 is 2-(2-pyridyl)ethyl, R.sub.4 is ethyl;
Compound 25: R.sub.1 is (2-chlorophenyl)methyl, R.sub.4 is
ethyl;
Compound 26: R.sub.1 is (2-thienyl)methyl, R.sub.4 is ethyl;
Compound 34: R.sub.1 is (R)-1-phenyl-2-propyl, R.sub.4 is
ethyl;
Another preferred subclass of the cardiovascularly active or
anti-hypertensive compounds of the present invention is shown by
General Formula 9, where the substituents R.sub.1, R.sub.2 and
R.sub.3 signify the same groups as in the compounds of General
Formula 8. The 5'-carboxamido substituents groups comprise, in this
subclass of compounds, aralkyl having 1 to 4 carbons in the alkyl
chain, unsubstituted or substituted in the aryl nucleus with
hydroxy, halogen, lower alkoxy or lower alkyl groups;
heteroarylalkyl having 1 to 4 carbons in the alkyl chain; and
heteroarylalkyl having 1 to 4 carbons in the alkyl chain,
unsubstituted or substituted in the heteroaryl nucleus with
hydroxy, halogen, lower alkoxy or lower alkyl groups. Thus, in the
structure symbolized by General Formula 9, n is an integer having
the values of 1 to 4, and Q is an aromatic nucleus, or aromatic
heterocycle, and Z is one or more H, hydroxy, halogen, lower alkoxy
or lower alkyl.
Specific examples of compounds of the subclass of general formula 9
are:
Compound 35 R.sub.1 is 3-pentyl and the 5'-carboxamido substituent
is phenylmethyl;
Compound 36 R.sub.1 is 3-pentyl and the 5'-carboxamido substituent
is 2-methoxyphenylmethyl;
Compound 37 R.sub.1 is 3-pentyl and the 5'-carboxamido substituent
is 2-thienylmethyl;
Compound 38 R.sub.1 is 3-pentyl and the 5'-carboxamido substituent
is 2-phenylethyl. ##STR6##
Yet another subclass of the compounds of the present invention is
shown in General Formula 10. In this subclass of compounds, the N-6
amino group of the purine moiety is substituted with a 3-pentyl
group, and the R.sub.1 substituent of the 5'-carboxamido group is
straight chain lower alkyl having 1-4 carbon atoms; hydroxy, lower
alkoxy or halogen substituted straight chain lower alkyl having 1-4
carbon atoms; cyclopropyl; secondary alkyl having 3-6 carbon atoms;
hydroxy, lower alkoxy or halogen substituted secondary alkyl having
3-6 carbon atoms; alkenyl having 3 to 6 carbon atoms; aralkyl
having 1 to 4 carbons in the alkyl chain; aralkyl having 1 to 4
carbons in the alkyl chain and substituted in the aryl nucleus with
hydroxy, halogen, lower alkoxy or lower alkyl groups;
heteroarylalkyl having 1 to 4 carbons in the alkyl chain; and
heteroarylalkyl having 1 to 4 carbons in the alkyl chain and
substituted in the heteroaryl nucleus with hydroxy, halogen, lower
alkoxy or lower alkyl groups. The second substituent on the
5'-carboxamido nitrogen, R.sub.4, is hydrogen, or straight chain
lower alkyl having 1 to 4 carbons. The R.sub.2 and R.sub.3
substituents on the hydroxyl groups of the ribofuranose moiety are
the same as described above in connection with the compounds of
General Formulae 7, 8, and 9.
Specific examples of compounds of the subclass of General Formula
10, where the R.sub.2 and R.sub.3 substituents are hydrogen,
are:
Compound 17: R.sub.1 is ethyl, R.sub.4 is H;
Compound 28: R.sub.1 is methyl, R.sub.4 is H;
Compound 29: R.sub.1 is isopropy, R.sub.4 is H;
Compound 30: R.sub.1 is 3-pentyl, R.sub.4 is H;
Compound 31: R.sub.1 is allyl, R.sub.4 is H;
Compound 32: R.sub.1 is (2-methyl)propyl, R.sub.4 is H;
Compound 33: R.sub.1 is cyclopropyl, R.sub.4 is H;
Compound 35 R.sub.1 is phenylmethyl, R.sub.4 is H;
Compound 36 R.sub.1 is 2-methoxyphenylmethyl, R.sub.4 is H;
Compound 37 R.sub.1 is 2-thienylmethyl, R.sub.4 is H;
Compound 38 R.sub.1 is 2-phenylethyl, R.sub.4 is H;
Compound 39 R.sub.1 is methyl, R.sub.4 is methyl;
Compound 40 R.sub.1 is n-butyl, R.sub.4 is methyl;
Compound 41 R.sub.1 is ethyl, R.sub.4 is ethyl; ##STR7##
The physical characteristics and biological activity of specific
examples of the compounds of the present invention are noted below
together with certain biological activity data. The tests showing
the biological activity of the compounds of the present invention
are discussed after description of the specific examples.
SPECIFIC EXAMPLES
Ethyl N.sup.6 -(3-pentyl)adenosine-5'-uronamide, (Compound 17) mp
176-177, uv .lambda.max(.epsilon.)=269 nm(18.1.times.10.sup.3) at
pH 7. Anal. Calculated for C.sub.17 H.sub.26 N.sub.6 O.sub.4
(378.44): C, 53.96; H, 6.93; N, 22.21. Found: C, 53.82; H, 6.95; N,
22.17. Molar potency ratio (mpr) 3.3.+-.0.25; anti-hypertensive
activity at 0.05 mg/kg (22,20,22).
Ethyl N.sup.6 -cyclohexyladenosine-5'-uronamide, (Compound 18) mp
133-135; uv.lambda.max(.epsilon.)=270(18.8.times.10.sup.3) at pH 7.
Anal. Calculated for C.sub.18 H.sub.26 N.sub.6 O.sub.4 (382.38): C,
55.37; H, 6.71; N, 21.52. Found: C, 55.34; H, 6.86; N, 21.42. Molar
potency ratio (mpr) 1.5.+-.0.24; anti-hypertensive activity at 0.1
mg/kg (13,17,15).
Ethyl N.sup.6 -(S)-1-phenyl-2-butyladenosine-5'-uronamide,
(Compound 19) mp 177-179; uv .lambda.max(.epsilon.)270
nm(19.2.times.10.sup.3) at pH 7; .alpha..sub.D.sup.25 =+27 c=1 in
95% ETOH. Anal. Calculated for C.sub.22 H.sub.28 N.sub.6 O.sub.4
(440.51): C, 59.99; H, 6.41; N, 19.08. Found: C, 59.89; H, 6.37; N,
19.06. Anti-hypertensive activity at 0.1 mg/kg (12,14,12).
Ethyl N.sup.6 -4-methoxyphenyladenosine-5'-uronamide, (Compound 20)
mp 189-190; uv .lambda.max(.epsilon.)287 nm(19.4.times.10.sup.3) at
pH 7; Anal. Calculated for C.sub.19 H.sub.22 N.sub.6 O.sub.4
(414.42): C, 55.07; H, 5.35; N, 20.28. Found: C, 55.16; H, 5.45; N,
20.23. Anti-hypertensive activity at 10 mg/kg (40,47,52).sup.+
Ethyl N.sup.6
-2-(3,4,5-trimethoxyphenyl)ethyladenosine-5'-uronamide, (Compound
21) mp 154-155; uv.lambda.max(.epsilon.)270.5
nm(15.7.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.23
H.sub.30 N.sub.6 O.sub.7 (502.53): C, 54.97; H, 6.02; N, 16.72.
Found: C, 55.14; H, 6.13; N, 16.71. Anti-hypertensive activity at
10 mg/kg (18,0,8).sup.+
Ethyl N.sup.6 -3-phenylpropyladenosine-5'-uronamide, (Compound 22)
mp 153-156; uv .lambda.max(.epsilon.)268 nm(17.6.times.10.sup.3) at
pH 7; Anal. Calculated for C.sub.21 H.sub.26 N.sub.6 O.sub.4
(426.48): C, 59.14; H, 6.15; N, 19.71. Found: C, 59.24; H, 5.91; N,
19.85. Anti-hypertensive activity at 10 mg/kg (39,40,39)..sup.+
Ethyl N.sup.6 -(R)-1-phenyl-ethyladenosine-5'-uronamide, (Compound
23) mp 144-147; uv .lambda.max(.epsilon.)270
nm(19.9.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.20
H.sub.24 N.sub.6 O.sub.4 (412.45): C, 58.24; H, 5.87; N, 20.06.
Found: C, 58.26; H, 6.00; N, 20.22. Anti-hypertensive activity at 1
mg/kg, rio detectable signal of blood pressure.
Ethyl N.sup.6 -2-(2-pyridyl)ethyladenosine-5'-uronamide, (Compound
24) mp 126-127; uv .lambda.max(.epsilon.)268.5
nm(20.5.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.19
H.sub.23 N.sub.7 O.sub.4 (413.44): C, 55.20; H, 5.61; N, 23.71.
Found: C, 55.38; H, 5.82; N, 23.87. Anti-hypertensive activity at
10 mg/kg (31,16,21)..sup.+
Ethyl N.sup.6 -(2-chlorophenyl)methyladenosine-5'-uronamide,
(Compound 25) mp 134-136; uv .lambda.max(.epsilon.)267.5
nm(19.4.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.19
H.sub.21 C1N.sub.6 O.sub.4.H.sub.2 O (450.89): C, 50.61; H, 5.14;
N, 18.64. Found: C, 50.85; H, 5.04; N, 18.49. Anti-hypertensive
activity at 5 mg/kg, no detectable signal of blood pressure.
Ethyl N.sup.6 -2-thienylmethyladenosine-5'-uronamide, (Compound 26)
mp 164-165; uv .lambda.max(.epsilon.)268.5 nm(21.2.times.10.sup. 3)
at pH 7. Anal. Calculated for C.sub.17 H.sub.20 N.sub.6 O.sub.4 S
(404.45): C, 50.49; H, 4.98; N, 20.78. Found: C, 50.46; H, 5.21; N,
20.81. Anti-hypertensive activity at 5 mg/kg (22,32,29).sup.+
2-Hydroxyethyl N.sup.6 -endo-2-norbornyladenosine-5'-uronamide,
(Compound 27) mp 132-134; uv.lambda.max(.epsilon.)270.5
nm(18.5.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.19
H.sub.26 N.sub.6 O.sub.5.H.sub.2 O (420.48): C, 54.27; H, 6.71; N,
19.99. Found: C, 54.22; H, 6.66; N, 19.90. Anti-hypertensive
activity at 1 mg/kg (8,33,36).sup.*
Methyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 28) mp
126-128; uv .lambda.max(.epsilon.)269 nm(18.5.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.16 H.sub.24 N.sub.6 O.sub.4 (364.41):
C, 52.74; H, 6.64; N, 23.06. Found: C, 52.66; H, 6.70; N, 23.16.
Anti-hypertensive activity at 0.5 mg/kg (14,17,17).
Isopropyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 29) mp
191-193; uv .lambda.max(.epsilon.)269 nm(18.3.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.18 H.sub.28 N.sub.6 O.sub.4
(392..46): C, 55.09; H, 7.19; N, 21.41. Found: C, 55.03; H, 7.37;
N, 21.27. Anti-hypertensive activity at 0.5 mg/kg (11,24,18).
3-Pentyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 30) mp
211-212; uv .lambda.max(.epsilon.)270 nm(17.9.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.20 H.sub.32 N.sub.6 O.sub.4 (420.52):
C, 57.13; H, 7.67; N, 19.98. Found: C, 57.35; H, 7.76; N, 19.81.
Anti-hypertensive activity at 20 mg/kg (6,21,17).
Allyl-N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 31) mp
169-170; uv .lambda.max(.epsilon.)269 nm(19.2.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.18 H.sub.26 N.sub.6 O.sub.4 (390.45):
C, 55.37; H, 6.71; N, 21.52. Found: C, 55.24; H, 6.97; N, 21.31.
Anti-hypertensive activity at 2.5 mg/kg (15,15,20).
(2-Methyl)-propyl N.sup.6 -3-pentyladenosine-5'-uronamide,
(Compound 32) mp 206-207; uv .lambda.max(.epsilon.)268.5
nm(16.9.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.19
H.sub.30 N.sub.6 O.sub.4 (406.49): C, 56.14; H, 7.44; N, 20.67.
Found: C, 56.22; H, 7.46; N, 20.76. Anti-hypertensive activity at
10 mg/kg (15,19,13).
Cyclopropyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 33)
mp 181-183; uv .lambda.max(.epsilon.)269 nm(20.0.times.10.sup.3) at
pH 7; Anal. Calculated for C.sub.18 H.sub.26 N.sub.6 O.sub.4
(390.45): C, 55.37; H, 6.71; N, 21.52. Found: C, 55.11; H, 6.65; N,
21.66. Anti-hypertensive activity at 0.25 mg/kg (21,21,28), molar
potency ratio (mpr) 2.3.
Ethyl N.sup.6 -(R)-1-phenyl-2-propyladenosine-5'-uronamide,
(Compound 34) mp 157-158; uv .lambda.max(.epsilon.)=270
nm(18.0.times.10.sup.3) at pH 7. .alpha..sub.D.sup.25 =-104.5.
Anal. Calculated for C.sub.21 H.sub.26 N.sub.6 O.sub.4 (426.48): C,
59.14; H, 6.15; N, 19.71. Found: C, 58.91; H, 6.10; N, 19.64. Molar
potency ratio (mpr) 4.3.+-.0.60;
Phenylmethyl N.sup.6 -3-penthyladenosine-5'-uronamide, (Compound
35) mp 174-175; uv .lambda.max(.epsilon.)269
nm(17.4.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.22
H.sub.28 N.sub.6 O.sub.4 (440.51): C, 59.99; H, 6.41; N, 19.08.
Found: C, 59.76; H, 6.34; N, 19.07. Anti-hypertensive activity at 5
mg/kg (18,26,22).
2-Methoxyphenylmethyl N.sup.6 -3-pentyladenosine-5'-uronamide,
(Compound 36) mp 176-178; uv .lambda.max(.epsilon.)269.5
nm(18.9.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.23
H.sub.30 N.sub.6 O.sub.5 (470.53): C, 58.71; H, 6.43; N, 17.86.
Found: C, 58.53; H, 6.68; N, 17.65. Anti-hypertensive activity at
10 mg/kg (12,18,18).
2-Thienylmethyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound
37) mp 160-161; uv .lambda.max(.epsilon.)237
nm(10.1.times.10.sup.3), 269.0 nm(17.4.times.10.sup.3) at pH 7;
Anal. Calculated for C.sub.20 H.sub.26 N.sub.6 O.sub.4 S (446.53):
C, 53.80; H, 5.87; N, 18.82. Found: C, 53.62; H, 6.00; N, 19.00.
Anti-hypertensive activity at 5 mg/kg (16,16,14).
2-Phenylethyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound
38) mp 203-204; uv .lambda.max(.epsilon.)268.5
nm(18.8.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.23
H.sub.30 N.sub.6 O.sub.4 (453.53): C, 60.78; H, 6.65; N, 18.49.
Found: C, 60.88; H, 6.67; N, 18.50. Anti-hypertensive activity at
40 mg/kg (17,13,15).
Dimethyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 39) mp
168-169; uv .lambda.max(.epsilon.)269 nm(18.7.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.17 H.sub.26 N.sub.6 O.sub.4 (378.44):
C, 53.96; H, 6.93; N, 22.21. Found: C, 53.71; H, 7.11; N, 22.34.
Anti-hypertensive activity at 2.5 mg/kg (25,23,17).
Methyl,n-butyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound
40) mp 139-141; uv .lambda.max(.epsilon.)270
nm(19.2.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.20
H.sub.32 N.sub.6 O.sub.4 (420.52): C, 57.13; H, 7.67; N, 19.98.
Found: C, 57.26; H, 7.50; N, 19.92. Anti-hypertensive activity at 1
mg/kg (31,21,27).
Diethyl N.sup.6 -3-pentyladenosine-5'-uronamide, (Compound 41) mp
148-150; uv .lambda.max(.epsilon.)269 nm(19.0.times.10.sup.3) at pH
7; Anal. Calculated for C.sub.17 H.sub.30 N.sub.6 O.sub.4 (406.49):
C, 56.14; H, 7.44; N, 20.67. Found: C, 56.42; H, 7.29; N, 20.67.
Anti-hypertensive activity at 1 mg/kg (10,13,11).
Dimethyl N.sup.6 -2-(2-chlorophenyl)-ethyladenosine-5'-uronamide,
(Compound 42) mp 129-131; uv .lambda.max(.epsilon.)268.5
nm(20.2.times.10.sup.3) at pH 7; Anal. Calculated for C.sub.20
H.sub.23 C1N.sub.6 O.sub.4 (446.90): C, 53.75; H, 5.19; N, 18.81.
Found: C, 53.91; H, 5.37; N, 18.59. Anti-hypertensive activity at 5
mg/kg (20,19,13).sup.+.
PROCESS FOR MAKING THE COMPOUNDS OF THE INVENTION
The compounds of the present invention are prepared in accordance
with a novel process of the invention from a suitably blocked
derivative of inosine-5'-uronic acid, such as
2',3'-O-isopropylideneinosine-5'-uronic acid (Compound 43).
2',3'-O-isopropylideneinosine-5'-uronic acid (Compound 43) is
readily obtained from inosine by treatment with acetone to block
the 2'- and 3'- hydroxy groups of the ribofuranose moiety, followed
by oxidation with chromic acid, in accordance with the published
procedure of R. R. Schmidt and H. J. Fritz, Chemische Berichte.,
103, 1867 (1970).
2',3'-O-isopropylideneinosine-5'-uronic acid (Compound 43) is
treated in accordance with the process of the present invention,
with a suitable inorganic acid halide, such as thionyl chloride, to
convert, in the same reaction step, the uronic acid moiety into a
uronic acid halide and to introduce a halogen substitutent into the
6 position of the purine moiety. In this regard it is noted that
the blocking groups of the 2' and 3' hydroxyl groups must be
capable of withstanding the conditions of this reaction, which is
advantageously conducted in neutral solvents, such as chloroform,
in the presence of dimethylformamide or other dialkylamides. The
isopropylidene blocking group serves well for this purpose.
Nevertheless, other ketal, acetal or even acyl blocking groups are
also suitable. Instead of thionyl chloride other inorganic acid
halides, such as thionyl bromide, may also be used. The product of
the just described first step of the novel reaction sequence is
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl 5-uronic
acid chloride]-9H-purine (Compound 44).
The reaction sequence leading to the compounds of the present
invention, using the example of
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl 5-uronic
acid chloride)-9H-purine (Compound 44) as the important
intermediate, is shown in Reaction Scheme 1. ##STR8##
REACTION SCHEME 1
6-chloro-9-[2,3-O-isopropylidene-.beta.-D-ribofuranosyl-5-uronic
acid chloride]-9H-purine (Compound 44) is preferably not isolated
in a pure state. Rather, it is reacted with an amine of the General
Formula 4 to displace the halide of the uronic acid moiety and to
provide compounds of the General Formula 5, wherein the halogen in
the 6 position of the purine nucleus is retained. This selective
displacement of the "acid chloride" group is readily conducted in
neutral solvents, such as chloroform, preferably at low
temperature.
The intermediates of General Formula 5, may be isolated in a
purified state. They are subsequently reacted with a nucleophilic
amine of General Formula 6 in a suitable solvent such as ethyl
alcohol, to displace the halogen substituent in the 6 position of
the purine nucleus. The displacement reaction is preferably
conducted in the presence of an acid acceptor, such as triethyl
amine. The blocking groups of the 2' and 3' hydroxyls of the
ribofuranose moiety are thereafter removed to provide the compounds
of the invention (General Formula 3). Removal of the isopropylidene
blocking groups is affected, for example, by heating with aqueous
hydrochloric acid. These steps are illustrated in the continuation
of Reaction Scheme 1. In the formulae shown in Reaction Scheme 1,
the definition of the substituent R groups is the same as was given
above in connection with the respective general formulae.
Specific examples of the steps of the novel process of the present
invention for the preparation of ethyl N.sup.6
-(3-pentyl)adenosine-5'-uronamide (Compound 17) and of N,N-dimethyl
N.sup.6 -(3-pentyl)adenosine-5'-uronamide (Compound 39) are given
below.
Actually, the invention of the herein disclosed novel process is
broader than the preparation of the herein disclosed compounds
having beneficial cardiovascular or anti-hypertensive properties.
In a broad sense, a multitude of N-6 and 5'-N substituted adenosine
5'-uronamides can be synthesized in accordance with the process of
the present invention. The compounds which are obtainable by the
process of the present invention include, in addition to the
compounds described above, those compounds wherein the carboxamido
nitrogen is mono or di substituted with alkyl, alkenyl, cycloalkyl,
aralkyl, and heterocyclyl groups. The carboxamido nitrogen (5'-N)
can also be a member of a saturated heterocyclic ring such as a
piperidine or morpholine ring.
An alternative process for the preparation of at least some of the
compounds of the present invention comprises the steps of oxidizing
N-6 substituted adenosine derivatives which are suitably protected
(for example by isopropylidene or benzyl groups) on the 2' and 3'
hydroxyl groups. The step of oxidation is conducted in analogy to
the procedure published by R. R. Schmidt and H. J. Fritz in
Chemische Berichte, 103, 1867 (1970). The N-6 substituted adenosine
derivatives can be obtained by reaction of
6-chloro-.beta.-D-ribofuranosyl-9H-purine with the suitable
amine.
The resulting uronic acid is then converted to the corresponding
acid halide by treatment, for example, with thionyl chloride, in
analogy to the process which was described above. The resulting
uronic acid halide is thereafter reacted with a primary amine
bearing the desired R.sub.4 and R.sub.5 substituents. After removal
of the protecting groups from the ribofuranosyl moiety, the
compounds of the present invention are obtained.
6-Chloro-9-[2,3-O-isopropylidene-5-ethylcarboxamido-.beta.-D-ribofuranosyl]
-9H-purine (Compound 45).
A mixture of 2',3'-O-isopropylideneinosine-5'-uronic acid (6.5 g,
20 mmols), thionyl chloride (4 ml, 53.3 mmols), dry
dimethylformamide (1.5 ml, 40 mmols) and dry chloroform (250 ml)
was refluxed for 4 to 5 hours. The chloroform was removed in vacuo
to give a syrup. The syrup was dissolved in dry chloroform (80 ml),
and the resulting solution was added to a mixture of ethylamine (14
mi) and dry chloroform (150 ml) at 10.degree. C. The mixture was
stirred for one hour at 10.degree. C., and then poured into cold
water (300 ml). The resulting organic layer was separated and
washed in succession with aqueous hydrochloric acid (10%,
2.times.200 ml), aqueous sodium bicarbonate solution (saturated,
1.times.200 ml) and water (1.times.100 ml), and dried over
magnesium sulfate. The chloroform solvent was removed in vacuo to
give 6.3 g (85% yield) of a slightly yellow solid. The product is
usable in the subsequent reaction steps without further
purification.
Ethyl N.sup.6 -(3-pentyl)adenosine-5'-uronamide, (Compound 17)
A mixture of
6-Chloro-9-[2,3-O-isopropylidene-5-ethylcarboxamido-.beta.-D-ribofuranosyl
]-9H-purine (Compound 45) (6.3 g, 17.1 mmols), 3-pentylamine (1.6
g, 18.4 mmols), triethylamine (4.7 ml, 34 mmols) and absolute
ethanol (200 ml) was refluxed for about 48 hours, or until thin
layer chromatography indicated complete reaction. The ethanol was
removed in vacuo and the product purified by chromatography on a
silica gel column eluted with chloroform/acetone 16:1. Evaporation
of fractions containing product yielded a syrup which was heated
for 1.5 hours with aqueous hydrochloric acid (1.0 N, 100 ml) at
70.degree. C. Upon cooling it yielded Compound 17 as white
crystals. Recrystallization from ethanol yielded white needles,
(4.5 g, 70% yield). The physical characteristics and analytical
data of Compound 17 were described above.
Dimethyl N.sup.6 -(3-pentyl)adenosine-5'-uronamide (Compound 39)
from 2',3'-O-isopropylideneinosine-5'-uronic acid (Compound 43)
A mixture of 2',3'-O-isopropylideneinosine-5'-uronic acid (5.0 g;
15.5 mmols) thionyl chloride (2.5 ml; 33.3 mmols) dry
dimethylformamide (1.25 ml; 18.1 mmols) and dry chloroform (170 ml)
was refluxed for 5 hours. The solvents were removed in vacuo to
give a syrup. The syrup was dissolved in dry chloroform (50 ml) and
the resulting solution was added to a mixture of dimethylamine (20
ml, 302 mmols) and dry chloroform (150 ml) at 10.degree. C. The
mixture was stirred for 15 minutes after the addition was complete,
and thereafter poured into cold water (300 ml). The organic phase
was separated and washed successively with water (1.times.100 ml),
10% aqueous hydrochloric acid solution (2.times.100 ml), saturated
aqueous sodium bicarbonate solution, and was thereafter dried with
anhydrous magnesium sulfate. The chloroform solvent was removed in
vacuo to give a syrup. The syrup was refluxed for 48 hours (or
until thin layer chromatography indicated complete reaction) with
3-pentylamine (2.3 ml; 20 mmols), triethylamine (2.8 ml, 20 mmols)
and anhydrous ethanol (100 ml). The solvent and volatile reagents
were removed in vacuo to give a syrup (blocked nucleoside). The
blocked (isopropylidine) nucleoside was purified by C-18 high
performance low pressure liquid chromatography (HPLPLC),
methanol-water (70%) being used as the eluent. The solvent was
removed in vacuo from the appropriate fractions, to yield a light
yellow solid which was thereafter heated at 70.degree. C. for 1.5
hours in 2N aqueous hydrochloric acid (100 ml). Cooling and
neutralization with solid sodium bicarbonate yielded Compound 39 as
a white syrup, which was crystallized from methanol/water to give
4.0 g (68%) of colorless needles. The physical characteristics and
analytical data of Compound 39 were described above.
BIOLOGICAL ACTIVITY AND PHARMACOLOGICAL PROPERTIES
The cardiovascular and anti-hypertensive activities of the
compounds of the present invention were determined in bioassays
conducted on dogs and spontaneously hypertensive rats.
More particularly, in one type of assay in which the activity of
the compounds of the present invention was determined, the
compounds to be tested are infused intracoronarily into either
open-chest anesthetized or conscious dogs. Adenosine has a
demonstrable coronary dilator effect under these conditions. The
concentration of the test compound in coronary plasma which causes
half-maximal vasodilation is designated ED-50.
More specifically, ED-50 is determined in the following manner.
Late diastolic coronary conductance (LDCC) of the experimental dog
is monitored through suitable instrumentation. Late diastolic
coronary conductance is measured at maximum coronary vasodilation
(peak reactive hyperemid), and is designated LDCC.sub.max. Late
diastolic coronary conductance is also measured at basal coronary
vasodilation, and is designated LDCC.sub.0.
The difference between instantaneously measured late diastolic
coronary conductance (LDCC) and basal late diastolic coronary
conductance (LDCC.sub.0) is expressed as a fraction of the
difference between maximum late diastolic coronary conductance
(LDCC.sub.max) and basal late diastolic coronary conductance
(LDCC.sub.0). Thus, LDCC is defined by Equation I. ##EQU1##
As the concentration of the test compound is varied, and the
corresponding LDCC is obtained through measurements and the
above-summarized calculations, data of an "LDCC versus
concentration" function or plot are obtained.
ED-50 is derived from these data by log-logit transformation of the
"LDCC versus concentration" plot; namely by solving the linear
regression of logit (LDCC) on log (concentration) for LDCC=0.5.
When ED-50 of a tested compound is compared to ED-50 of adenosine
in the same dog, as is set forth in EQUATION II, then the resulting
molar potency ratio (mpr) provides good comparison of the
cardiovascular activity of the tested compound with cardivascular
activity of other compounds in the same or other experimental dogs.
Thus, molar potency ratio (mpr) is a useful measure of the
cardiovascular vasodilatory effect, and hence of the utility of the
tested compounds. The greater the vasodilatory effect of a tested
compound, the larger the corresponding molar potency ratio (mpr).
##EQU2##
For a more detailed description of the bioassay used for
determining molar potency ratios, reference is made to an article
written by Olsson et al., and titled "Coronary Vasoactivity of
Adenosine in the Conscious Dog", Circulation Research, 45, 468
(1979).
Molar potency ratios of the specific examples of the compounds of
the present invention are listed above next to the detailed
description of the specific compounds. These data demonstrate that
the compounds are cardiovascularly active.
In another assay for the anti-hypertensive activity of the
compounds of the invention, blood pressure of unanesthetized,
unheated spontaneously hypertensive rats (SHR) is measured
indirectly (through a tail cuff) usually at 2, 4, and 6 hours after
oral administration of a single dose of the compounds of the
invention. Reduction in mean blood pressure by more than ten per
cent (10%) indicates anti-hypertensive activity. The test itself,
is well established in the art and need not described here in
further detail.
The data obtained in the hypertensive rat (SHR) assay are indicated
next to the description of the compounds. In the data, the
percentage reduction of blood pressure in 2, 4 and 6 hours after
the single oral dose is indicated in parentheses. A .sup.* sign
after the data shows that the measured reduction of blood pressure
occurred 1, 2, and 3 hours after the oral dose; a .sup.+ sign
indicates that the measured reduction occurred in 1, 2 and 2.5
hours after the oral dose. The data demonstrate the
anti-hypertensive activity of the compounds of the invention.
An assay for the affinity of some of the compounds of the present
invention for R.sub.a receptors employs a modification of the
radioligand displacement method described by Fox and Kurpis in The
Journal of Biological Chemistry, Volume 258 pages 6952-55 (1983).
Briefly, this method comprises the steps of incubating [.sup.3
H]NECA and the analogs to be tested, with human placenta membrane
particles, a source of R.sub.a receptors. The particles are then
filtered, washed with a buffer to remove unbound ligand and then
the amount of bound radioligand is measured. By varying the
concentration of the competing analog one may estimate an index of
binding affinity, IC-50, the concentration of which causes
half-maximum displacement of [.sup.3 H]NECA. Using [.sup.3 H]NECA
in this assay instead of [.sup.3 H]-2-chloroadenosine is a
modification of the original method.
The compounds of the present invention were found to compete
weakly, or not at all, with [.sup.3 H]ethyladenosine-5'-uronamide
at R.sub.a receptor sites of human placenta.
The foregoing indicates that the compounds of the present invention
are selective to R.sub.a receptors of the cardiovascular system.
Such selectivity would not be expected on the basis of prevailing
prior art theory.
Further advantages of the compounds of the present invention
include their inability to undergo phosphorylation in the
5'-position, and their stability to acid. Therefore, the
therapeutic effect of the compounds of the present invention is
unlikely to be eliminated by the action of phosphorylating enzymes,
and the compounds are unlikely to be incorporated into DNA or RNA.
As is known, incorporation into RNA or DNA is likely to cause
teratogenic, mutagenic or carcinogenic effects.
Moreover, because the compounds of the present invention are stable
to acid (they survive heating with 1N aqueous HCl for 1.5 hour at
70.degree. C.) they are capable of surviving the acidic conditions
prevailing in the stomach. Therefore, they are suitable as drugs
for oral administration to humans and animals.
Various modifications of the herein disclosed invention, in terms
of structural modifications of the invented compounds and also in
terms of making or using the same, may become readily apparent to
those skilled in the art in light of the above disclosure. For
example the compounds of the present invention may be administered
as pharmaceutically acceptable salts.
Inasmuch as the compounds of the present invention are useful as
cardiac vasodilators, cardivascular, and particularly as
anti-hypertensive agents in mammals, domestic animals and humans,
various modes of administering the compounds will be apparent to a
person having average skill in the art. Such modes of administering
the compounds include oral and topical administration, and
intravenous infusion. One having average skill in the art may
readily prepare suitable formulations for the above-mentioned and
other modes of administering the compounds of the invention.
In light of the foregoing, the scope of the present invention
should be interpreted solely from the following claims, as such
claims are read in light of the disclosure.
* * * * *